Black opal, a rare amorphous SiO₂ variety, results from the interaction of silica with organic matter and therefore hints at traces of life, including the early Earth and Mars. The Volyn occurrence is one of the few examples of black opal worldwide and is the unique case of a pegmatitic occurrence in a granite; its age is at least 200 Ma. The structure consists of micrometer-large sphere-like arrangements of nano-sized grains and shows shape relicts of fossils, known from Volyn as "kerite".